So, I totally didn't make this, but it was hanging up in my classroom last week (Thanks, Terri!), and I totally love it (and the kids REALLY enjoy it). It's super easy to make. All you need is a piece of poster board (Dollar Store sells them for $.50), 2 paper cups, 2 paper towel roll insides, a basket or bowl, beads/counters/beans, etc. and a marker to draw the plus sign! These are all simply taped to the poster board using packaging tape. My older students love to experiment with bigger…